Internal-combustion engine



Nov. 4 1924.,

W. J. STILL INTERNAL COMBUSTION ENGINE Filed Jan.

' Sheets-Sheet Nov, 4 1924,

w. J. STILL INTERNAL COMBUSTION ENGINE Filed Jan. 4 192 2 Sheets-Sheet Patented N V.14,,1924.;

UNITED srATEs To all it 4% concern.

WILLIAM JOSEPH STILL, OF LONDON, ENGLAND.

' summits-COMBUSTION Enema,

STIL a subject of the i'ng of Great Britaim land, resident of London, England, have inventedcertain new and useful Improvements inandRelating toJInternal-Combustion Engines, of which the following is a specification. a V

This invention relates to cylinders and pistons for internal combustion engines, and

has for its object to provide a piston and cylinder construction which will permit of t e employment of cylinders and pistons of greater area than as at present possible;

provided for the piston, all the heat taken up by-the piston as a result of combustion has to'be transmitted to the cylinder walls and absorbed in the waterof the' cylinder jacket, and it will 'be readily seen that if the rate of'heat absorption is insuflicient the iston soon becomes unduly hot, its centre mg, of course, the hottest point.

" For this reason in building engines of large power the methodat presentadopted is-to provide a multiplicity of cylinders each with itsown accessories such as fuel valves, inlet and exhaust valves or ports, and it will be readily appreciated that this involves complications and practical difficulties when it is remembered that the combustion chamber' of the cylinders must each receive an equal quantit of air andgfuel, and i ition mustbe equa ly perfect for all the cy inders if the engme is to erformeflicientIy. f

structed 'considerable difiic ulty .is experienced in timing the engines so as'to obtain equal conditions in all cylinders at all loads, andif it were contemplated to pro "vide say 42cylinder's the practical difliculties of obtainmgequal distribution and efiithe total plston area open to each combustion chamber that the parts of the area most remote from the influence of the cooling medium are considerably nearer to said how concentric Application filled January 4, 19521. flerialwno. 484,988..

piston giving the same effective area. a

The invention further involves two particular practical embodiments one of which 1s the construction of the piston of annular ,formand the other OfWhlOh consists individing. the totalpistonarea into a number of, separate pistons all open to the same combustion chamber and all connected to a common cross head In the former of these arrangements cooling pam be eii'ected;v by

j acketsarranged both outside and inside the l l annulus and in thelatter casethe separate It is well known that the maximum .diameterpossible in practice for the cylinders and pistons; of internal combustion engines is limited owingtothe heat stresses. ,Ex- 7 cept where special methods of cooling are 20 pistons can becompletely surrounded by the cooling medium It is thus possible to, provide a much larger total piston area open to each 'combustion chamber than would be orm. a l l 'In the accompanying drawings I have ilossiblewith a single piston of ordinary llustrat'ed various. embodiments of my inventiondiagrammatically,

Fig. 1' being, a transverse sectional elevation ,of a double acting four cycle engine inder and piston of a two cycle engine havmg M n annular .piston in accordance with myinvention. v

Fig.3 is a view similar to Fig. 2 showing annular pistons can be pro- Fig. 4is'a sectional; elevation illustrating "the alternative method of dividing up the piston area into separate elements all open to a single; combustion chamber and all cone nected to'a'commoncr s-h in twelv cy n sets as atp @011- a Fi 5 is a diagrammatic'plan showing the dlsposition'of the separate. pistons which cumulatively form the total piston area;

Referring to these drawings and particularly to Fig. 1 the numeral 1 designates an annular piston which slides in the annular cylinder 2and is maintained in gas tight engagement bymeansof packingrings 3 fitted in its inner periphery similar packing rings 4 fitted in its outer periphery and packing rings 5 fitted in the cylinder end 6.

'An external cooling jacket 7 is provided and there islalso an internal space 8 for the circulation of the coolingmedium. It is thus clear thattthe piston is sub'ected to theinfluence' of the cooling me ium from both sides and although the piston area can be considerable there is no part of it which cannot be effectively cooled. I

The operation of the engine will be well understood the combustible charges entering the combustion chambers through the auto matic inlet valves vS) while exhaust takes,

circulation of the cooling medium which can thus act upon both-walls of the annular piston which co-operates with the inlet ports 14 and exhaust ports 15 in the man-* ner usual in twocycle engines.

Fig. 3 illustrates the possibility of erate withthe inlet and exhaust ports20 and '21 respectively which of course are common to the two annular cylinders 18 and 19 which are open to a common combustion space 22. Here again each of the annular pistons is subjected to cooling from both sides by means of the'cooling medium circulated through the cooling jackets or-spaces 23, 24 and 25. The numeral 26 designates the cylindercover which is bolted by means of suitably disposed bolts 27 to the-outerwall of the cylinder structure and it will be understoodthat both the pistons are connected together by a common cross head 28 which is in turn coupled to the engine crank.

shaft in the usual way.

An alternative arrangement by which the desired effective cooling can be obtained is illustrated in Figs. 4 and.5. In this-arrangement the total piston area is made up of a number of separate pistons 28 each'opcrating in its own cylinder 29 but all these cylinders are connected to one combustion chamber or space30 and all'the'pistons are coupled to a common cross-head 31 and operate in unison. In this arrangement each cylinder is] surrounded by cooling jackets and thus [although the cumulative piston area open to the combustion chamber is considerably more than has hitherto been possible in one cylinder effective cooling is provided while the complications of separate cylinders with their separate valves and accessory devices is obviated.

i g The practical advantages of this form of my inventionmay be realizedby assuming, by way of example, that a cylinder of 16" diameter is satisfactory in practice but that a 26" diameter cylinder. is not practical. The'required power can be obtained according to my invention with a single'combustion chamber by providing three cylinders prov'id-, ing annular pistons conoentrical y one within the other. These pistons 16 and 17 slide in the annular cylinders 18 and 19'and co-op surface for a ter were employed united to a common combustion chamber, they would-at the same speed and working pressure-give a power output corresponding to that of a cylinder of over 40 diameter, and the heat stresses within the cylinders would vary but little from those obtaining in a single cylinder of. 16" diameter. Seven cylinders could be arranged as indicated in Fig. 5 or in a group of six in a circle around a central one but the combustion chamber in such cases would probably'besubject to certain disadvantages, and for this reason I prefer, in most cases, to obtain the desired relation of surface to volume by the use of the an-' nular forms of cylinder and piston hereinbefore described. 7 I j 7 In these annular pistons the radial width of the piston can be regulated according to the speed and workinv' pressure of the engineso asto control the rate of heat flow within safe limits, slow speed engines, operating on low mean effective pressures, having pistons that are wider and have more given diameter than those designed for hlgher speed and pressure. Both the foregoing arrangements are, however, in accordance withlthe same general principle. I j v What I claim and desire to secure by Let.- ters Patent is':'

1. A large internal combustion engine comprising a cylinder having a central chamber, a jacketed outer wall, a circular screen in the form o'fan annulus disposed centrallyand longitudinally within the jacketed outer wall and arranged to shield eve part of the inner surface of the outer wal from some of the heat particles produced by combustion and contained within the cylinder and fcoacting with'said jacketed outer wall to form anannular chamber therebetween, said cylinder also having a chamber 'tocontain a cooling medium arranged cent'rally in said cylinder'an'd spaced from the first named central chamber, means for supplying cooling fluid to the outer jacketed wall, the interior of the circular screen and the said second named central chamber, andan annular piston arranged in sliding contact with both the outerwall of the cylinder and the central circular screen. I I y 2. A large internal combustion engine comprising acylinder having a central chamber, a jacketed outer wall, a circular screenin the formof an annulus disposed centrally and longitudinally within the jacketed outer.

wall and arranged to shield every art of the inner surfaceof the jouter wal from some of the heat part cles produced bycombustion and contained within the cylinder chamber, means for supplying cooling vfluid 10 to the outer jacketed wall, the interior of the circular screen and the said second named central chamber, and an annular piston arranged in sliding contact with both the outer wall of the cylinder and the central circular. 15 screen.

In witness whereof I alfix m si ature.

WILLIAM J OSEP S ILL. 

